J. M. Barker

AN EASY SYNTHESIS OF 3-AMINO- AND 3-NITROTHIOPHENE

Abstract 3-Amino- and 3-nitrothiophene are readily made by the decarboxylation of the corresponding thiophene-2-carboxylic acids which are easily prepared from the commercially available methyl 3-aminothiophene-2-carboxylate.

A RAPID CONVERSION OF 3-OXOTHIOLANES INTO 3-AMINOTHIOPHENES

ABSTRACT 3-Oxotetrahydrothiophenes can be rapidly converted into 3-aminothiophenes by refluxing with hydroxylamine hydrochloride in a polar solvent, usually acetonitrile.

Nitration of methyl-3-hydroxy- and 5-methyl-3-hydroxy-thiophene-2-carboxylate, and some chemistry of the products

The nitration of methyl-3-hydroxythiophene-2-carboxylate furnishes two products, the lower melting of which was previously thought to be the 4- (3) and the other the 5-isomer (2); these assignments have been reversed on the basis of carbon-13 NMR. data and the revised structures have been confirmed both by O to N acyl migrations and by the preparation of the first examples (20) and (23) of the thieno[3,4-b][1,4]oxazine ring system from derivatives of the 4-nitro isomer.

A SYNTHESIS OF 2-ACYL-3-HYDROXYTHIOPHENES

Abstract 2-Acyl-3-hydroxythiophenes have been made by the reaction of the anion of a mercaptoketone with dimethyl acetylenedicarboxylate to give a hydroxythiophene ester which is then hydrolysed and decarboxylated.

Novel thiophene-based macrocycles related to azacrown ethers

A range of compounds containing two 3-oxygenated thiophene rings linked through the oxygen atoms by a variety of alkyl and heteroalkyl chains has been prepared and subjected to electrophillic substitution, at C(2) and C(2′), giving, inter alia, bis-Mannich bases containing 14- to 22-membered rings; preliminary X-ray diffraction studies of representative metal complexes are in hand.

The preparation of thiophene-based azacryptand Mannich bases

The preparation of cryptand-like structures, incorporating four thiophene rings, was undertaken. A variety of approaches were considered, but a stepwise process commencing from the readily available α,ω-bis(2-formyl-3-thienyloxy)alkanes of the type ArO-Z-OAr (where Ar = 2-formyl-3-thienyl and Z = heteroalkyl chain) yielded excellent results. A range of open chain and cyclic Mannich bases incorporating one or two macrorings was prepared via reduction of open chain and macrocyclic imines derived from the heteroalkyl-bridged bisaldehydes. Tosyl and acetyl derivatives of the reduced products, viz. the intermediate secondary amines were prepared; the latter exhibited diastereoisomerism.